The present invention relates to a random number generating device that generates a random number by the behavior of a microcomputer.
When electrically-powered equipment (electric power tools, electrically operated machines, and so on), which operate in response to power supply from batteries, and battery chargers, which charge batteries, are mounted with batteries that are not regular or appropriate, sometimes, the equipment get broken, or the batteries abnormally generate heat.
Accordingly, this type of equipment has been known in which, when the battery is mounted on the equipment, a random number is employed to determine (certify) whether or not the mounted battery is appropriate (e.g., see Specification of U.S. Pat. No. 7,941,865).
Specification of U.S. Pat. No. 7,941,865 suggests employing, as the random number, noise bits (low-order hits) being an AD converted value obtained by an A/D converter.
Further, a random number generating circuit that generates a random number is known in which a voltage control oscillator generates oscillation outputs by receiving unstable power source voltage, the oscillation outputs are counted for a predetermined period of time, and the counted value of the oscillation outputs is outputted as a random number (e.g., see JP3492494).